The Doctor speaks to the voice who does not believe they are travellers and are spies for the Menoptra. It attacks the Tardis but it emerges Vicki has realigned the fluid link to reactivate the power. Zarbi are stalking the remaining free Menoptra Vrestin. The voice offers the Doctor his freedom in return for assistance defeating the Menoptra invaders. The Doctor is coerced into bringing out his astral map to pinpoint the invasion force. Vicki is retained as a hostage while the Doctor and Ian fetch the map. While inside the Doctor treats Ian's injured face. The Doctor likens the voice to the ant queen and asks Ian to escape & track down Barbara. He escapes leaving the Doctor & Vicki with the Zarbi. While wandering the tunnels of the base he is pursued by Zarbi. The Doctor detects transmissions from the Menoptra fleet and learn they are planning to land at the crater of needles, where the slaves are held. Ian is trapped by the Zarbi but a Venom grub cutting through the wall allows him to escape at which point he meets Vrestin. On the pretext of fetching equipment, the Doctor sends Vicki into the Tardis and she emerges with what he says is the wrong box, containing a spider specimen which the Zarbi recoils from in terror. Vrestin tells Ian that Vortis is their planet, and they are reclaiming it not invading. Menoptra and Zarbi lived side by side. The Zarbi were enslaved by the dark power of the Animus which caused the Zarbi's base, the Carsinome to appear and grow. The Menoptra were driven off planet to one of the moons attracted to the planet by the Animus. They have returned to Vortis to destroy the Carsinome before it envelops the planet. Vrestin was part of the scouting spearhead. They leave for the Crater of Needles to rescue their friends there. They are waylaid by Zarbi but as they are cornered the ground gives way beneath their feet burying them.

Oh that's much more like it. I didn't get on with the first two episodes but this one is much better. Some explanation of what's going on, some action and some plot advancement. Nice one, best episode of the story thus far. The more I watch Doctor Who in order, the more convinced I become that it's natural unit isn't the story but the episode. The whole episode was recorded in one session on these early stories and some weeks they pull it off ok, and in others it goes pear shaped.

This episode introduces us properly to and explains the Animus. The Animus is the very first of a Doctor Who staple, the disembodied intelligence. Almost always evil these crop up regularly in Doctor Who over the years. As well as the Animus controlling the Zarbi here, Troughton fights the Great Intelligence controlling the Yeti in The Abominable Snowmen & The Web of Fear while the Nestene Consciousness with it's Autons fight the Pertwee Doctor in his debut Spearhead from Space and it's sequel the Terror of the Autons. Tom Baker battles the Mandragora Helix and the Fendahl while McCoy fights Fenric. About the only "good" disembodied intelligence we see in the whole series is Rassilon, the leader of the Time Lords, who appears in the Five Doctors (does he reside, post death, in the Time Lords' Matrix ?)